The invention relates to a slow moving electrical machine, such as a motor or generator or a combined motor-generator, as described in the introductory part of claim 1.
A slow moving electrical machine may be used for different purposes, e.g. for land or sea vehicles, for hoisting and lifting equipment and in some cases also for power generating. Such machines are known as xe2x80x9cpermanently magnetized synchronous machinesxe2x80x9d (PMSM). But some of these machines are not suitable for an intended, specific purpose, particularly depending on the conditions of efficiency and space demand.
A growing demand for energy economization, due to energy supply and energy costs, exists. This particularly applies to motors/generators intended for vehicles and other purposes being powered by batteries. To reduce the battery capacity required and extend the operational range or the power output of battery powered applications. The highest efficiency possible is necessary.
In some situations, the need for space economy is also a critical factor.
The main object of the invention is to create an improved electrical machine, particularly a motor, which is more energy economical and space saving than prior art machines for similar purposes. Generally, it is an object to create an energy efficient electrical machine, which can compete with existing synchronous machines for industrial purposes, but at the same time the machine should be suitable for being powered by a battery, to be used for operating vehicles and other equipment without continuos more power.
It is particularly important to provide an electrical machine suitable for slow rotation, with electronic drive control, to avoid the need for gears. It is also desirable to be able to scale the machine within large limits according to the purpose and also be able to use identical components for different sizes.
Other objects linked to particular areas of use will appear from the description of embodiments to follow.
This machine has proved suitable as a motor for e.g. vehicles, thrust propellers and winches. It can be manufactured in different sizes. Within one size range, identical elements can be used for different purposes, e.g. powder cores, magnets, iron yokes for magnets, coils and the plastic frames for the powder cores. This standardizing of elements will reduce the manufacturing costs.
It is possible to adapt an electrical machine according to the invention, particularly as a motor, to different purposes, e.g. for powering wheel chairs and other vehicles, for powering thrusters on ships, for winches and for process applications demanding slow rotation. The need for gears is eliminated, and the costs will be lower than for corresponding known power units. The rotational control and the conversion from motor to generator application in combined use can be achieved with electronic controls based on known principles, which in most cases can be incorporated into the housing of the machine.
For motor applications, the electrical machine according to the invention has several advantages.
low vibrations under operation, and thus low noise,
high starting torque
high efficiency, particularly when using laminated cores,
high flexibility in design, particularly with regard to the main dimensions
it can easily be provided with double or multiple stator and can thus be easily scaled up
based on standard components, particularly powder cores, magnets, iron yokes, coils and forms with coils.
The invention will bring the greatest advantage used in connection with an axial field, i. e. axially magnetizing. But it will also work with a radial field, when easy mounting and demounting is particularly important.
Further details of the invention will appear from the following description of embodiments.